Exhauster inlet venturi

Abstract

An inlet venturi for coal-side exhauster fan structure used to deliver pulverized coal to a combustion chamber. Generally, the inlet venturi has an axial length comparable to that of the exhauster fan inlet, resulting in a shallow, smooth transition angle from the venturi to whizzer ring or similar structure for guiding the coal flow into the center of the fan assembly. The inlet venturi includes a back plate or collar portion which prevents eddy effects and pressure drop between the venturi throat and the exhauster fan inlet, and further serves to accurately position the venturi in the exhauster fan inlet. The inventive inlet venturi structure additionally permits the removal of some or all of the "whizzer" structure commonly used on such fans, resulting in substantial savings in power needed to drive the fan.

What is claimed is: 
     
       1. In a pulverizer exhauster fan having a housing, a fan mounted to rotate in the housing, a circular inlet coaxial with the fan for delivering pulverized coal flow to the fan for subsequent radial diversion to an outlet in the housing, and structure defining an inlet into the center of the fan, the invention comprising: an inlet venturi mounted in the circular inlet concentric with the fan inlet, the venturi extending from the intake end of the circular inlet to a throat proximate the intake end of the fan inlet, the venturi further including an annular collar portion extending from the throat to the wall of the circular inlet.   
     
     
       2. Apparatus as defined in claim 1, wherein the annular collar is angled forward and overlies the fan inlet. 
     
     
       3. Apparatus as defined in claim 1, wherein the annular collar extends upwardly essentially perpendicular to the flow of pulverized coal through the circular inlet. 
     
     
       4. Apparatus as defined in claim 3, wherein the throat and the annular collar are aligned with the outlet end of the circular inlet. 
     
     
       5. Apparatus as defined in claim 4, wherein the inlet venturi further includes a cylindrical extension extending past the annular collar into the fan housing to a point proximate the fan inlet. 
     
     
       6. In a pulverizer exhauster fan having a housing, a fan mounted to rotate in the housing, a circular inlet coaxial with the fan for delivering pulverized coal flow to the fan for subsequent radial diversion to one or more outlets in the housing, and structure defining an inlet into the center of the fan, the invention comprising: an inlet venturi mounted in the circular inlet, the venturi decreasing in diameter in the direction of pulverized coal flow through the inlet, the venturi inlet end being positioned at the intake of the circular inlet, the venturi having a throat of minimum diameter immediately adjacent the fan inlet, the throat being concentric with and having a diameter slightly smaller than the diameter of the fan inlet.   
     
     
       7. Apparatus as defined in claim 6, the venturi further including an annular collar portion extending from the throat to the wall of the circular inlet. 
     
     
       8. Apparatus as defined in claim 7, wherein the annular collar is angled forward and overlies the fan inlet. 
     
     
       9. Apparatus as defined in claim 7, wherein the annular collar extends upwardly essentially perpendicular to the flow of pulverized coal through the circular inlet. 
     
     
       10. Apparatus as defined in claim 9, wherein the throat and the annular collar are aligned with the outlet end of the circular inlet. 
     
     
       11. Apparatus as defined in claim 10, wherein the inlet venturi further includes a cylindrical extension extending past the annular collar into the fan housing to a point proximate the fan inlet. 
     
     
       12. Apparatus as defined in claim 5, wherein the throat is smaller than the diameter of the fan inlet. 
     
     
       13. In a pulverizer exhauster fan having a housing, a fan mounted to rotate in the housing, a circular inlet coaxial with the fan for delivering pulverized coal flow to the fan for subsequent radial diversion to one or more outlets in the housing, and structure defining an inlet into the center of the fan, the invention comprising: inlet venturi means in the circular inlet for directing coal flow from the intake end of the circular inlet to the intake end of the fan inlet, the inlet venturi means having a throat concentric with and immediately adjacent the fan inlet, the venturi means further including means for preventing eddies in the circular inlet between the throat portion and the outlet end of the circular inlet.